Simply plug it in and your petʹs water will remain open all winter, even in extremely cold temperatures. It's perfect for outdoor dogs or multiple outdoor cats.Thermostats inside the Thermal-Bowl automatically respond to changes in temperature to keep the unit running optimally and prevent ice formation. There's no switch to turn on and, when temperatures are sufficiently cold, the Thermal-Bowl will begin to warm after being connected to a power outlet. DO NOT immerse your Thermal-Bowl in water or other liquids when cleaning. Wipe your Thermal-Bowl inside and out with a damp cloth. A mild detergent may be used but be sure all detergent has been removed before watering your pet or wildlife.